Simplifying Terrain geometry for Analysis

Hi All,

Does anyone know of a tool/addon which could take exported terrain geometry and turn it into larger planes (therefore less surfaces) in order to create simplified meshes for CFD analysis?

We want to evaluate the wind flow around a terrain to determine the best spot to locate a group of buildings, however the terrain is quite large and detailed and I do not want to have to try tackle manually drawing in planes to simplify it.

Any recommendations would be appreciated =)